Early Fuel Evaporation System: Operation
When ignition switch is turned to the "ON" position, voltage is applied to a thermo switch located in intake manifold. If engine coolant temperature is below a calibrated value, the thermo switch is in an "ON" condition and a circuit is completed to the heater, allowing current to flow.
The heater, incorporating a positive temperature coefficient semiconductor element, increases in temperature and then self-regulates at a calibrated temperature. This is in effect except at high engine speeds when air/fuel flow will reduce the temperature below regulated value. When coolant temperature reaches calibrated value, thermo switch turns off and current to heater is cut off.
EFE heater located in carburetor insulator gasket.